[Some properties of hydrophilic addition-type silicone impression materials]

Addition-type silicone impression materials have the characteristic of low wetting by water; therefore, they are sometimes inconvenient in clinical use. However, hydrophilic addition-type silicone impression materials are said to be improved in this characteristic. In this study, the physical properties of two kinds of hydrophilic addition-type silicone impression materials, namely, Hydrophilic EXAFLEX and EXPRESS, were investigated and compared with the traditional addition-type silicone impression materials. Compression set, strain in compression, consistency, and contact angles of the salivary droplet on the these impression materials were measured in accordance with ADAS no. 19. The following results were obtained: 1. Each compression set of HEM, HEL, EPM, EPL, EPE (hydrophilic addition-type silicone impression materials), having superior property in compression recovering, was less than 0.1%, they were equivalent to one-seventh of that of the traditional addition-type silicone impression materials. 2. Strain in compression of HEM, HEL, EPM, EPF was bigger than that of the traditional addition-type silicone impression materials. 3. Consistency of HEM, HEL, EPM, EPL, EPF was smaller in fluidity than that of the traditional addition-type silicone impression materials. Among all impression materials in this study, only with HEM and HEL could a difference in consistency between wet films and dry films be recognized. 4. Contact angles of all hydrophilic addition-type silicone impression materials were smaller than those of the traditional addition-type silicone impression materials. They were equivalent to two-thirds of that of the traditional addition-type silicone impression materials, and improvement in wetting property of these hydrophilic addition-type silicone impression materials was observed.